The average gdp per capita refers to a. the balance of trade between nations per year b. the average life expectancy of a nation’s people c. the quality of a nation’s transportation systems d. the economic output of each individual in a country per year

d.the economic output of each individual in a country per year

GDP means Gross Domestic Product, and It is an economic indicator that measures the economic output of a country in one year. In order to determine the average GDP per person of a country, it is necessary to divide the GDP of the entire country by the population. The average GDP pro-capita is often used to determine the wealth of a nation. 

Tropical climate is experienced in the nothern countries of south america

Answer (b) they're often rural migrants with no title to housing or rights to established businesses